Prevention of Surgical Site Infections: Considerations in Measuring Effectiveness

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Prevention of Surgical Site Infections
Considerations in Measuring Effectiveness
Michele L. Pearson, MD Division of Healthcare
Quality Promotion National Center for Infectious
Diseases
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Objectives

• Provide overview of epidemiology of surgical site
  infections (SSI)
• Discuss SSI prevention strategies
• Highlight current surveillance systems for SSI
• Provide overview of HICPAC/CDC process for
  developing recommendations for prevention
  healthcare-associated infections

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Public Health Importance of Surgical Site
Infections

• In U.S., gt40 million inpatient surgical
  procedures each year 2-5 complicated by
  surgical site infection
• SSIs second most common nosocomial infection (24
  of all nosocomial infections)
• Prolong hospital stay by 7.4 days
• Cost 400-2,600 per infection (TOTAL 130-845
  million/year)

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CDC Definition of Surgical Site Infections
SSI level classification Incisional SSI
- Superficial incisional skin and subcutaneous
tissue - Deep incisional involving deeper
soft tissue Organ/Space SSI - Involve
any part of the anatomy (organs and spaces),
other than the incision, opened or
manipulated during operations
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Cross Section of Abdominal Wall Depicting CDC SSI
Classifications
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Source of SSI Pathogens

• Endogenous flora of the patient
• Operating theater environment
• Hospital personnel (MDs/RNs/staff)
• Seeding of the operative site from distant focus
  of infection (prosthetic device, implants)

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Microbiology of SSIs
1986-1989 (N16,727)
1990-1996 (N17,671)
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Microbiology of SSIs

• Unusual pathogens
• Rhizopus oryzea - elastoplast adhesive
  bandage
• Clostridium perfringens - elastic bandages
• Rhodococcus bronchialis - colonized health
  care personnel
• Legionella dumoffii and pneumophila - tap
  water
• Pseudomonas multivorans - disinfectant
  solution
• Cluster of unusual SSI pathogens ? formal
  epidemiologic investigation

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Pathogenesis of SSI

• Relationship equation
  Dose of bacterial contamination x
  Virulence Resistance of
  host
  
  SSI Risk

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SSI Risk Factors

• Age
• Obesity
• Diabetes
• Malnutrition
• Prolonged preoperative stay
• Infection at remote site
• Systemic steroid use
• Nicotine use

• Hair removal/Shaving
• Duration of surgery
• Surgical technique
• Presence of drains
• Inappropriate use of antimicrobial prophylaxis

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Perioperative Preventive Measures
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Role of Antimicrobial Prophylaxis (AP) in
Preventing SSI

• Refers to very brief course of an antimicrobial
  agent initiated just before the operation begins
• Should be viewed as an adjunctive preventive
  measure
• Appropriately administered AP associated with a
  5-fold decrease in SSI rates

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Importance of Timing of Surgical Antimicrobial
Prophylaxis (AP)

• Prospective study of 2,847 elective clean and
  clean-contaminated procedures
• Early AP (2-24 hrs before incision) 3.8 Postop
  AP (3-24 hrs after incision) 3.3 Periop AP
  (lt 3 hrs after incision) 1.4 Preop AP (lt2 hrs
  before incision) 0.6

Classen, 1992 (NEJM 326281-286)
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Impact of Prolonged Surgical Prophylaxis

• DESIGN Prospective
• POPULATION CABG patients (N2641)
• Group 1 pts who received lt 48 hours of AP
• Group 2 pts who received gt 48 hrs of AP

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Impact of Prolonged Surgical AP

• OUTCOMES
• Incidence of SSI
• Isolation of a resistant pathogen
• RESULTS 43 of patients received AP gt 48 hr
• SSI Incidence
• lt48 hrs group 8.7 (131/1502) vs
• gt48 hrs group 8.8 (100/1139), p1.0
  Antimicrobial resistant pathogen
• OR 1.6 (95 CI 1.1-2.6)

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Enhanced Perioperative Glucose Control in
Diabetic Patients

• DESIGN Prospective, sequential study
• POPULATION Diabetic patients undergoing cardiac
  surgery (N2467) during 1987-1997
• Controls pts who received intermittent subQ
  insulin (SQI)
• Treated pts who received continuous
  intravenous (IV) insulin

Furnary AP Ann Thorac Surg, 2000
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Enhanced Perioperative Glucose Control in
Diabetic Patients

• OUTCOMES
• Blood glucose lt200 mg/dl in first two days
  postop
• Incidence of deep sternal SSI
• RESULTS
• SQI group 2.0 (19/968) vs
• IVI group 0.8 (12/1499), p0.01

Furnary AP Ann Thorac Surg, 2000
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Supplemental Perioperative O2

• DESIGN Randomized controlled trial, double
  blind
• POPULATION Colorectal surgery (N500)
• INTERVENTION 30 vs 80 inspired oxygen during
  and up to hours after surgery
• RESULTS SSI incidence 5.2 (80 O2) vs 11.2
  (30 O2), p0.01

Greif, R, et al , NEJM, 2000
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Pre-operative Antiseptic Showers/Baths
Most studies examine effects on skin colony
counts antiseptic showering decreases colony
counts Few studies examine effect on SSI
rates No Shower Shower Cruse, 1973
2.3 1.3 Ayliffe, 1983 4.9
5.4 Rooter, 1988 2.4 2.6
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Pre-operative Shaving/Hair Removal
Seropian, 1971 Method of hair removal Razor
5.6 SSI rates Depilatory 0.6 SSI rates No
hair removal 0.6 SSI rates Timing of hair
removal Shaving immediately before 3.1 SSI
rates Shaving ? 24 hours before 7.1 SSI
rates Shaving gt24 hours before 20 SSI rates
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Pre-operative Shaving/Hair Removal
Multiple studies show - Clipping
immediately before operation associated with
lower SSI risk than shaving or clipping the
night before operation
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Surgical Attire

• Scrub suits
• Cap/hoods
• Shoe covers
• Masks
• Gloves
• Gowns

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Surgical Technique

• Removing devitalized tissue
• Maintaining effective hemostasis
• Gently handling tissues
• Eradicating dead space
• Avoiding inadvertent entries into a viscus
• Using drains and suture material appropriately

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Parameters for Operating Room Ventilation

• Temperature 68o-73oF, depending on normal
  ambient temp
• Relative humidity 30-60
• Air movement from clean to less clean
  areas
• Air changes gt15 total per hour gt3 outdoor
  air per hour
  
  

American Institute of Architects, 1996
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Role of Laminar Air Flow (Ultraclean Air) in
Preventing SSI

• Most studies involve only orthopedic operations
• Lidwell et al 8,000 total hip and knee
  replacements
  ultraclean air SSI rate ?3.4 to 1.6
  antimicrobial prophylaxis (AP) SSI rate
  ?3.4 to 0.8
  ultraclean air AP SSI
  rate ?3.4 to 0.7

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Status of SSI Surveillance
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CDC Surveillance Systems
NNIS DSN NaSH
Nosocomial infections in critical care and surgical patients Bloodstream and vascular access infections in dialysis outpatients Exposure to bloodborne pathogens TB skin testing and exposure Vaccine history, receipt, and adverse events
1999-2004
1996-present
1970-2004
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Characteristics of NNIS Hospitals, 2000

• 300 hospitals
• 58 are MAJOR TEACHING
• 10 are Graduate Teaching
• 15 are Limited Teaching
• 16 are Non Affiliated Hospitals
• Bed Size
• Median 360 beds
• No facilities lt 100 beds

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Variables Collected in Surgical Patient
Component, NNIS

• Age
• Sex
• ASA score
• Wound class
• Trauma-related
• Type of anesthesia
• Emergency vs elective
• Duration of surgery
• Length of postoperative stay
• Infection site (skin/soft tissue, organ space)
• Pathogen
• Mortality
• Hospital demographics (bed-size, affiliation)

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SSI Risk Index

• From the U.S. National Nosocomial Infections
  Surveillance (NNIS) system
• American Society of Anesthesiologists (ASA) score
• 1 to 5, from 1normal, healthy to 5patient
  not expected to survive for 24 hours with OR
  without operation
• Wound Class
• Clean, clean-contaminated, contaminated, dirty
• Duration of surgery

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Surgical Site Infection (SSI) Rates By Risk
Category,
NNIS System, 1986-1999
16
Low risk
12
Medium
8
SSIs per 100 operations
low risk
Medium
high risk
4
High risk
0
1992
1993
1994
1995
1996
1997
1998
1999
1986-90
Years
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SSI Definitions Period of Surveillance

• Infection occurs within 30 days after the
  operative procedure if no implant is left in
  place or within 1 year if implant is in place and
  the infection appears to be related to the
  operative procedure

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Challenges to Surveillance for SSIs
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What Is NHSN?
Integration of CDCs three patient and healthcare
personnel surveillance systems

• NNIS
• NaSH
• DSN

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NHSN Premises

• Maintain the goals of predecessor systems
• Minimize data collection and manual data entry
  burden
• Streamline existing surveillance protocols
• Increase capacity for capturing electronic data
  (e.g., Laboratory information systems, operating
  room, pharmacy, clinical, administrative
  databases)
• Extensible web-based application

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Priority Areas for NHSN Development

• Inclusion of process measures linked to outcomes
• Surgical prophylaxis
• Central line insertion practices
• Completion of HCP Safety Component
• NaSH ? NHSN
• Influenza pilot vaccine coverage and use of
  antiviral medications

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How do we develop policy?
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Healthcare Infection Control Practices Advisory
Committee (HICPAC)
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Healthcare Infection Control Practices Advisory
CommitteeMISSION

• Advise the US Secretary of Health and the
  Director of CDC regarding the practice of
  infection control and strategies for
  surveillance, prevention and control of
  antimicrobial resistance, and related adverse
  events in healthcare settings

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CDC/HICPAC GUIDELINE SCOPE

• TARGET AUDIENCE
• clinicians
• infection control professionals
• public health officials
• regulators
• TARGET SETTINGS
• Inpatient
• Outpatient
• Home care
• Long term care

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Ranking Scheme for HICPAC Recommendations (2001)

• CATEGORY IA. Strongly recommended for all
  hospitals and strongly supported by well-designed
  experimental or epidemiologic studies.
• CATEGORY IB. Strongly recommended for all
  hospitals and viewed as effective by experts in
  the field and a consensus of HICPAC based on
  strong rationale and suggestive evidence, even
  though definitive scientific studies may not have
  been done.
• CATEGORY IC. Required for implementation, as
  mandated by federal or state regulation or
  standard. CATEGORY II. Suggested for
  implementation in many hospitals. Recommendations
  may be supported by suggestive clinical or
  epidemiologic studies, a strong theoretical
  rationale, or definitive studies applicable to
  some but not all hospitals.
• NO RECOMMENDATION UNRESOLVED ISSUE. Practices
  for which insufficient evidence or consensus
  regarding efficacy exists.

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CDC/HICPAC GuidelineRATING SYSTEM

• CATEGORY EVIDENCE PRACTICE
• IA/IB STRONG RECOMMENDED
• IC LACKING REQUIRED BY REGULATION
• II GOOD SUGGESTED
• NO REC INSUFFICIENT UNRESOLVED
• CONTRADICTORY

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Challenges/Issues

• Subject matter experts vs. methodologic experts
• Resources for systematic reviews
• Limited randomized trials
• User needs vs available science (e.g., expansion
  to non-hospital settings)

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Healthcare Infection Control Practices Advisory
CommitteeGUIDELINE FORMAT

• PART I Provides review and synthesis of
  available research on guideline topic and
  established scientific rationale for
  recommendations
• PART II Provides summary of practice
  recommendations
• PART III Provides performance indicators for
  institutions to monitor success in
  implementing recommended practices

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Summary

• Prevention of SSI require a multifaceted approach
  targeting pre-, intra-, and postoperative factors
• Current surveillance systems do collect data on
  perioperative processes
• Increasing shift of surgical procedures to
  outpatient settings and decrease in postoperative
  length of stay complicate surveillance efforts
• Incidence is generally low so studies would
  require large sample size
• Some prevention practices (e.g. hand hygiene)
  would be difficult to study using traditional
  randomized controlled trial research design

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PREVENTION IS PRIMARY!
Protect patientsprotect healthcare
personnel promote quality healthcare! Division
of Healthcare Quality Promotion
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Division of Healthcare Quality Promotion (DHQP)
website
To obtain HICPAC guidelines visit the

• http//www.cdc.gov/ncidod/hip/default.htm